1. Field of the Invention
The present invention generally relates to supporting mechanisms involving optical pickup devices, and more particularly to a mechanism for supporting a guide shaft on a chassis for use in an optical disc apparatus.
2. Related Art
An optical disc such as a digital versatile disc (DVD) is a recording medium containing information along concentric or spiral tracks. In an optical disc apparatus, the optical disc is loaded on a turntable by a disc loading device, and is then rotated by a spindle motor. As the disc rotates, an optical pickup device travels in a radial direction of the optical disc and projects a laser beam onto tracks of the optical disc. The laser beam emitted by the optical pickup device is incident on the optical disc, for recording or reading information to or from the optical disc. Accordingly, a feeding mechanism is usually provided in the optical disc apparatus, for guiding and driving the optical pickup device to move in the radial direction of the optical disc.
FIG. 5 is a top plan view of parts of an optical disc apparatus 9, including a conventional feeding mechanism 90 for feeding an optical pickup device 92. The optical disc apparatus 9 also has a chassis 91, and the feeding mechanism 90 is attached to the chassis 91. The feeding mechanism 90 includes a pair of parallel guide shafts 93, a fixing seat 95, three adjustable seats 96, and a driving means 94. The fixing seat 95 and the adjustable seats 96 are fastened on the chassis 91 in two parallel alignments, each receiving an end of the pair of guide shafts 93 therein. In this way, the pair of guide shafts 93 is supported above the chassis 91, with two lateral sides of the optical pickup device 92 being respectively slidably engaged on the guide shafts 93. Thus, the path of movement of the optical pickup device 92 is precisely controlled. The driving means 94 is installed on the chassis 91 substantially parallel to the pair of guiding shafts 93, and generates a driving force applied to the optical pickup device 92.
The rapid advancement of multimedia applications has spawned systems that store information more compactly. In particular, the distance between adjacent recording pits of a modern optical disc is less than previously. This in turn requires that the laser beam generated by the optical pickup device 92 perpendicularly radiates to the optical disc when recording or reproducing information. Thus the guide shafts 93 should be precisely parallel to the optical disc, at exactly the same height to the optical disc.
Therefore, each adjustable seat 96 of the above-described feeding mechanism 90 usually includes a receiving chamber (not shown) at which a spring (not shown) is installed. The corresponding end of the corresponding guide shaft 93 is supported on the spring. An adjusting screw 97 is engaged in a top of the adjustable seat 96, and an end of the adjusting screw 97 extends into the receiving chamber and pushes the end of the guide shaft 93 supported on the spring. As a result, the ends of the guide shafts 93 are positioned in the receiving chambers of the adjustable seats 96 after being adjusted to respective desired locations.
However, it is inconvenient to install the springs in the adjustable seats 96. This is because the springs set in the receiving chambers of the adjustable seats 96 are very small. Therefore, referring to FIG. 6, an improved adjusting base 96′ has been devised. The adjusting base 96′ is integrally formed as a single piece, and includes an elastic support 960′ at a top thereof. The elastic support 960′ has a hook end 961′. A receiving chamber 962′ is defined under the elastic support 960′, and a recess 964′ defined in a front wall of the adjusting base 96′ communicates with the receiving chamber 962′. Therefore the end of one of the guide shafts 93 (shown in FIG. 5) can be inserted through the recess 964′ into the receiving chamber 962′, so that the hook end 961′ of the elastic support 960′ downwardly presses the end of the guide shaft 93. In order to adjust the height of the end of the guide shaft 93, an adjusting screw (not shown) is inserted into the receiving chamber 962′ from a bottom of the adjusting base 96′. However, it is inconvenient to assemble the associated optical disc apparatus. This is because the ends of the guide shafts 93 have to be inserted into the receiving chambers 962′ of the adjusting bases 96′ from the fronts of the adjusting bases 96′.
Therefore, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies related to inconvenient assembly.